1. Field of the Invention
This invention relates generally to static structures and more particularly to precast decking panels and associated connecting structures that are used as components of bridges.
2. Description of the Related Art
In the construction of bridges, the traffic supporting deck is often formed of discrete decking panels formed of precast concrete with steel reinforcement and additional structures for mounting and supporting them on the bridge. The precast decking panels are supported on the bridge beams and positioned side by side and sometimes end to end across the bridge.
An advantage of precast bridge decking panels is that they can be manufactured in a controlled environment and under closely controlled manufacturing parameters instead of being formed in place at a bridge site where their fabrication is subject to unpredictable, variable or harsh weather conditions and where transportable equipment is required for forming the bridge decking. Consequently, precast bridge decking panels can be fabricated to meet uniform size and high quality standards. Also, in the event of a decking failure, the uniformity and transportability of decking panels allows the relatively rapid replacement of one or more decking panels in a bridge, thereby minimizing the length of time that a bridge is closed for repairs.
Some of the most desirable characteristics of a bridge decking panel design are ease of installation, durability over years of use, stability under both normal traffic and under unusual adverse conditions, and ease of replacement in the event of a failure. One problem that has been experienced with some prior art decking panels is that the decking panels are attached to the supporting beams with structures, including bolts or studs, that require a hole in the concrete. After installation, the hole is filled with a grout material. Unfortunately, with the passage of time the grout material sometimes comes out to the hole as a result of bridge vibration caused by traffic and, in cold climates, also caused by freezing and thawing of water that seeps into cracks in the grouting. Loss of the grout leaves a hole in the deck and exposes the attachment structures to water, and in some climates to salt, which allows corrosion of the attachment parts and can also permit movement of the decking panels.
As with most construction projects, ease of installation is important because it translates into a reduction of the time required to install the decking panels and therefore results in a lowering of the cost of a project. However, ease of installation can not compromise bridge and decking panel strength and integrity. Both safety and bridge longevity require that the decking be held securely in place on the support beams and also resist any relative movement of the decking with respect to its support beams as the bridge withstands years of vibration and loading from traffic, especially from heavy vehicles. Stability requires that the bridge decking panels be constructed and attached to the beams in a manner that strongly resists lateral or longitudinal movement of the deck panel on its support beam, twisting or bending of the support beams and lifting from the support beams in the event of flood conditions.
Ease of replacement of a decking panel is desirable because, if a decking panel can be easily and rapidly removed and replaced, both the repair cost and the length of time that a bridge is out of service or partially closed for repairs are minimized.
It is therefore an object and feature of the invention to provide a precast decking panel that has no holes through the deck and has no structural or load supporting structures that are covered by or encased in a grout material.
It is another object and feature of the invention to provide a bridge decking panel with a fastening system and structures that can be installed easily and quickly.
It is another object and feature of the invention to provide bridge decking panels that are fastened in a secure and stable manner to the bridge support beams and to each other in a manner the resists relative motion of the decking panels with respect to the support beams.
It is yet another object and feature of the invention to provide a bridge decking panel that can be easily removed from its installed location on a bridge to permit its replacement within a relatively short time interval, such as overnight, and to do so without damaging bridge components that remain on the bridge for fastening a new decking panel in place on the bridge.
It is still another object and feature of the invention to provide a bridge decking panel that permits abutting panels to be connected together end to end by a continuous steel connection across the entire bridge.
Another object and feature of the invention is to provide a method for constructing bridge decking panels in accordance with the present invention.